This invention relates generally to manufacturing of Micro Electromechanical System (MEMS) devices, and more specifically, to attaching dies of MEMS devices to chip carriers.
Micro-electromechanical systems (MEMS) include electrical and mechanical components integrated on the same substrate, for example, a silicon substrate. Substrates for MEMS devices are sometimes referred to as dies. The electrical components are fabricated using integrated circuit processes, while the mechanical components are fabricated using micromachining processes that are compatible with the integrated circuit processes. This combination makes it possible to fabricate an entire system that fits within a chip carrier using standard manufacturing processes.
One common application of MEMS devices is utilization within inertial sensor. The mechanical portion of the MEMS device provides the sensing capability for the inertial sensor, while the electrical portion of the MEMS device processes the information received from the mechanical portion. Examples of inertial sensors that utilize MEMS devices include gyroscopes and accelerometers.
The MEMS production process involves the placement of the operational portion of the MEMS device, sometimes referred to as a micro-machine, within a chip carrier or housing, which is then hermetically sealed. In one known placement process, the die or substrate on which the operational portion of the MEMS device is formed is attached to gold contacts in the carrier using a thermocompression bonding process. However, this thermocompression process involves use of forces that sometimes result in damage to the die, e.g., cracks in the die. The cracks in the die can result in reduced strength in the bond between the chip carrier and the die. Since MEMS devices are often utilized in high gravitational force (high-G) environments, the bond strength between the chip carrier and the die is important. Should the chip carrier and the die become separated, operation of the MEMS device could be compromised.